Enable NPAPI if policy has plugin policies.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 49853f5b889e6d9e842bff354cdbd0853f517551..d206d552c4d2c70c539a9175eb51a5a085527b8c 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -2113,6 +2113,11 @@
       'browser/upgrade_detector_impl.cc',
       'browser/upgrade_detector_impl.h',
     ],
+    # Policy sources used if plugins are enabled.
+    'chrome_browser_policy_plugin_sources': [
+      'browser/plugins/enable_npapi_plugins_policy_handler.cc',
+      'browser/plugins/enable_npapi_plugins_policy_handler.h',
+    ],
     'chrome_browser_predictor_sources': [
       'browser/predictors/autocomplete_action_predictor.cc',
       'browser/predictors/autocomplete_action_predictor.h',
@@ -3287,6 +3292,9 @@
             ['OS=="win" or OS=="mac" or desktop_linux==1', {
               'sources': [ '<@(chrome_browser_policy_desktop_sources)' ],
             }],
+            ['enable_plugins==1', {
+              'sources': [ '<@(chrome_browser_policy_plugin_sources)' ],
+            }],
             ['OS=="android" or OS=="ios"', {  # Mobile.
               'sources': [ '<@(chrome_browser_policy_mobile_sources)' ],
             }, {  # Non-mobile.